1. Field of the Invention
This invention is directed toward a controller for controlling the unwinding of wire from a reel in a container. The invention is particularly directed toward a controller for controlling the unwinding of welding wire being fed to a robotic welder.
2. Description of the Related Art
Passive controllers are used to prevent the coils of wire on the reel from becoming tangled with each other as the wire is being unwound off the reel and fed to a robotic welding machine. If a controller were not used, the top wire coils, because of the manner in which they are wound to form the reel, could spring up when unwinding and become snarled or tangled with each other causing stoppages in the feeding of the wire. Any downtime to clear the snarls/tangles is costly.
The known controllers usually take the form of a flat ring which rests on the top of the end of the coil from where the wire is being fed, the ring moving down slowly, by gravity, as the wire feeds and the height of the reel diminishes. The presence of the ring on the end of the reel prevents the top coils from springing up and becoming tangled with each other. The ring usually has tabs extending radially outwardly for keeping it centered within the container holding the reel. Examples of ring shaped controllers are shown in U.S. Pat. Nos. 4,869,367 and 5,845,862.
There are problems however associated with the known rings. Rings of the type shown in U.S. Pat. No. 4,869,367, with a smooth, circular inner edge, do not prevent the wire being fed from pulling out one or more additional coils from under the ring which coils can become tangled above the ring. Rings of the type shown in U.S. Pat. No. 5,845,862 use fingers extending radially inwardly from the inner edge of the ring to make it more difficult for wire loops to escape from under the inner edge of the ring during wire feeding. However, when these rings are used with containers having a central core, the fingers abut the core and create additional friction which can slow the ring from dropping down as the height of the reel diminishes during unwinding. If the ring separates from the top end of the reel, there is room for the top wires to be pulled out and become tangled. The ring can be made heavier to minimize the effects of friction from the inner fingers but this adds to the cost of the rings. Further, the known rings, with inwardly extending radial fingers, do not feed the wire as smoothly from the reel since the wire must ride inwardly up each finger with tension increasing and then drop down back to the inner edge of the ring with little or no tension when it clears the end of the finger.
It is the purpose of the present invention to provide a controller that minimizes the escape of wire coils from under it, particularly inwardly from under it, during wire feeding. It is another purpose of the present invention to minimize the escape of the wire coils while minimizing friction on the controller during operation. It is a further purpose of the present invention to more smoothly feed the wire off the coil to minimize tangling. It is another purpose of the invention to provide a relatively simple, inexpensive and easily manufactured controller.
In accordance with the present invention the controller is in the form of a flat ring having flexible flaps extending inwardly from the inner edge of the ring. The inwardly directed flaps are sized to make it more difficult for the upper coils of wire to escape inwardly from the ring and yet to prevent the flaps from contacting an inner core if one is employed with the container. The flaps are also shaped and formed to guide the wire off the reel relatively smoothly and without tangling. The flaps are shaped to have a wire guiding edge that curves gently inwardly to a release point on the flap. The flap is also formed to have the release point be the highest point on the flap, the flap preferably curved upwardly to the release point. As the wire is moved gradually inwardly and upwardly over each flap, the flap, being flexible, moves upwardly as well before releasing the wire to the next adjacent flap. Thus the wire is guided more smoothly from each flap to the next.
The invention is particularly directed toward a controller for controlling the dispensing of wire from a reel of wire positioned within a container, the wire dispensed from one end of the reel with the other end of the reel sitting on the bottom of the container. The controller has a main body member in the shape of a flat ring sized to rest within the container on the one end of the reel. The ring has concentric, circular, inner and outer edges. The controller includes flexible, wire guide flaps on the inner edge of the ring, the guide flaps extending radially inwardly. Each guide flap has the general shape of a shallow triangle with the apex of the triangle farthest from the ring and the base of the triangle adjacent the ring.